Plesiomonas shigelloides is an oxidase-positive, fermentative, Gram-negative rod currently classified as a member of the family Vibrionaceae. Several reports have implicated the organism as a cause of sporadic and epidemic diarrheal disease, and indicated that P. shigelloides is a significant cause of both locally acquired and traveler's diarrhea. We isolated one strain of P. shigelloides from a 27-year-old woman who recently traveled to Thailand. The isolate showed typical cultural and biochemical characteristics of P. shigelloides. The results of the antimicrobial susceptibility test showed that the pathogen was susceptible to all tested antimicrobial agents with the exception of ampicillin.